This invention related to a method for mounting components and an apparatus therefor and more particularly to an improved arrangement that permits the accurate picking up and mounting of components and a method for performing such operations.
There are a wide variety of applications wherein components are picked up from a feed section where they are delivered and moved to and placed at an accurate location. A wide variety of devices are employed for actually picking up the components. Frequently such pick up devices employ vacuum nozzles for picking up the components.
A specific application for this type of apparatus and method is in the making of printed circuit boards. With such printed circuit boards, it is common to employ a device called a "chip mounter" that picks up small components such as integrated circuits, resistors or capacitors at a feed section and places them on a printed circuit board. Vacuum nozzles are frequently employed as the pick up devices.
In order to render such devices more versatile, it has been proposed to provide an arrangement wherein the form and type of pick up nozzle employed may be readily changed so as to suit particular components. This nozzle changing may be done either manually or automatically.
The criticality for accurately mounting such components is readily apparent. However, in the process of mounting the nozzle, mistakes may be made even if the apparatus functions automatically and these mistakes can result in inaccurate mounting of the components and other problems.
It is, therefor, a principle object of this invention to provide and improved apparatus and method for mounting components employing interchangeable pick up devices.
It is further object of this invention to provide: a method and apparatus that employs such types of pick up devices and which is operative to sense certain characteristics of the pick up device.
One way in which the method and apparatus functions to sense the pick up nozzle before the component is picked up so as to determine if the correct pick up nozzle is installed.
One of the operations that may be performed on the component once it is picked up by the pick up device is a sensing operation that will sense the orientation of the component relative to the pick up device so as to make a corresponding correction in the movement of the component to the mounting position so that it will correctly mounted. One type of device for such sensing involves rotation of the component in front of an optical sensor.
In addition to the problems of pick up misorientation, frequently it is possible that the pick up device will pick up the component not only at an orientation other than desired but the component actually incorrectly picked up. For example, the component normally has a lower surface that is intended to positioned on the device in which it is to be mounted such as a printed circuit board or the like. However, if the component is picked up off center it may actually rotate from the normal orientation so that the surface that is to be mounted will not be facing downwardly. If an attempt is made to mount the component in this orientation, damage can result. If, however, separate measures need be taken both to determine the orientation of the article as picked up and also whether the article has been picked up properly, the speed of the machine can be slowed considerably.
Therefor, it is a still further object of this invention to provide an improved method and apparatus for performing a single operation that is effective both to sense the orientation in which the component has been picked up and also to determine whether the component has been correctly picked up.
It is a still further object of this invention to provide an improved and simplified method and apparatus by which the correct picking up of a component by a pick up device may be determined.